<html>
    <head>
        <title>Test</title>
        <style>


        div {
          var(x): 0px;
          var(y): 0px;
          size:400dip;
          background: radial-gradient(var(x,0px) var(y,0px), 200dip 200dip, red, yellow, green, blue, rgba(255,0,255,0.5) );
        }


        </style>
        <script type="text/tiscript">

          $(#eye) << event mousemove (evt) {

            // update CSS variables x,y 
            this.style.variables {
              x : px(evt.x),
              y : px(evt.y)
            };
            this.refresh();
            
          }


        </script>
    </head>
    <body>
       <div #eye>move mouse over it</div>
    </body>
</html>